Question

PLEASE HELP!!
1.) In guinea pigs, rough fur (F) is dominant over smooth fur (f). What percent of the F2 generation would be homozygous dominant when a homozygous rough fur guinea pig is crossed with a homozygous smooth fur guinea pig?

2.)A person’s second toe is sometimes longer than their big toe. This condition is due to a dominant gene (L). What percent of the kids would you expect to have long second toes when a heterozygous man (Ll) marries a homozygous recessive woman (ll)?

3.)Facial dimples in man are dominant over no dimples. Show the expected children of a marriage between a woman with no dimples and a man with dimples whose mother did not have any facial dimples. What percent of the children would you expect to have dimples?

4.) In hamsters, short legs are dominant over long legs. Use the five-point plan to show how two short-limbed hamsters could have offspring with long limbs. If this one pair of hamsters were to have a total of 40 young, how many of the 40 would you expect to have short limbs?

6.) Free earlobes (E) in humans is dominant over attached earlobes (e). What would be the percent of free earlobes in the offspring when a man homozygous for free earlobes marries a woman who is heterozygous for free earlobes?

7.) The Basenji is a breed of dog noted for its inability to bark. When a Basenji is mated with a Beagle, all of the eight puppies can bark. How would you describe the genotype of the Basenji in genetic terms?

8.) Webbed fingers and toes in humans are due to a rare dominant gene (F). What percent of the offspring would you expect to have normal fingers and toes when a man heterozygous for webbed fingers and toes marries a woman with normal hands and feet?

Answer 1

I cannot for the life of me remember what this table is called, but it's the table with which all of your questions can be answers.

I'll work through number 2 as an example.

We're given that the man is (Ll) and that the woman is (ll). So we will make a table:\[\left[\begin{matrix} & l & l \\ L & & \\ l & & \end{matrix}\right]\]Then in each of the four spaces we will combine the what is in the first elements of each row and column. So with that table above we have:\[\left[\begin{matrix} & l & l \\ L & Ll & Ll\\ l & l l & l l \end{matrix}\right]\]Since we know that (ll) presents as the big toe being longer than the middle, and that (Ll) presents as the middle toe being longer than the big one, we can see that 50% of the children should have a middle toe that is longer than their big toe.


As a second example, number 4:

Short legs are dominant over long legs, so let's have S represent short legs and s represent long legs. If we have two short leg hamsters, the only way for them to have long legged offspring is if they were both heterozygous. So the table would like this:\[\left[\begin{matrix} & S & s \\ S & SS & Ss\\ s & Ss & ss \end{matrix}\right]\]From this we can see that 50% of the children would be heterozygous, and 25% would be homozygous dominant. The remaining 25% would be homozygous recessive. So if these two hamsters had 40 children, we would expect that 25% of them would have long legs, which would in this case be 10.

Does all that make sense?

Answer 2

punnet square
if at least this questions were pinpointed, they wouldn't have to ask so many times the same thing...

Answer 3

Ahh right. It's been quite some time since my last bio class.

Answer 4

i don't even know whats the translation for punnet square in my language, portuguese..
i just saw so many questions about this, and i fixed its name.

Answer 5

google translate say flowers :)

Answer 6

so... what are the answers?

Answer 7

Use the punnet squares like I showed you for the other questions.

Answer 8

is that it.

Answer 9

Yep

Answer 10

NIce one Aylin - you shouldn't tell someone the answers when they could figure it out themselves and actually learn something!